1. Field of the Invention
The present invention relates to an ink tank system using a replaceable ink tank for supplying ink to a print head of an ink jet printer for ejecting ink drops to printing sheets. The present invention also relates to a replaceable ink tank used in the ink tank system.
2. Description of the Related Art
A piezo-ink jet system is known in which a small amount of ink is momentarily pressurized using a piezoelectric element to eject ink droplets to the printing sheet. A bubble ink jet system is also known in which a small amount of ink is momentarily heated to generate bubbles and ink drops are ejected toward printing sheets by the action of the pressure of expanding bubbles.
In the printing mode of jetting ink drops, liquid ink is stored in a tank (ink tank), and ink is supplied to a printer head from the tank. Here, for example, when a large-sized poster is print-outputted or in another case of a large printing sheet, ink consumption is large. Accordingly, it is proposed that the ink tank be designed to be replaceable.
For example, a system is proposed in which an air pump is provided on the side of a printer body and pressurized air is fed into an ink tank from the air pump to force-feed ink to a printer head. In this system, a connector needs to be disposed between the printer main body and the ink tank, by which an air supply channel for feeding the pressurized air to the ink tank and an ink supply channel for supplying ink from the ink tank to the print head of the printer unit can be disconnected.
In the ink-jet printing system, since an ink drop jetting port of the print head is remarkably small, a slight dust contaminated in ink may clog the jetting port of the nozzle, thereby causing failure. Although the ink tank containing a quantity of ink is delivered to a user in a sealed condition, dust may enter the tank together with air especially from a pressurized air supply system when the user exchanges the ink tank for a new one.
To solve the problem, it is assumed that an air filter is provided in an air supply channel of the tank so that air surely passes through the air filter before entering the tank. In this case, however, while the ink tank is transported, the ink in the tank adheres to the air filter and solidifies. Therefore, there raises a problem that resistance increases when air passes through the air filter and the ink cannot be smoothly force-fed to the printer body.